Use GitHub actions for CI (#689)

Replace use of Travis CI with GitHub Actions.  Actions are more flexible and have the advantage that they are copied with the repository, so we don't need to set them up again each time the repository moves or is cloned.

This started out as a straightforward port of the Travis CI configuration, but I ended up with a slightly different organization.  There are 2 main workflows:

- the "Tests" workflow in `tests.yml` which runs:

  * unit tests, for all versions of Python supported by GitHub actions
  * installation tests on all the runner platforms supported by GitHub, using the default `python` binary there

- the "Publish" workflow in `publish.yml` which creates a Docker image; publishing is triggered only on completion of the "Tests" workflow on the `master` branch, and is aborted immediately if any of the tests is not successful.  Pull requests should *not* be published automatically, as contributors may then publish images using secrets stored on the `master` branch.

.github/workflows/publish.yml

@@ -0,0 +1,69 @@
+name: Publish released code
+
+on:
+  workflow_run:
+    workflows: ["Tests"]
+    branches:
+      - master
+    types:
+      - completed
+
+jobs:
+  dockerhub:
+    name: Build and upload Docker image
+    runs-on: ubuntu-latest
+    steps:
+
+    - name: Exit early if tests were unsuccessful
+      if: github.event.workflow_run.conclusion != 'success'
+      run: |
+        echo "Tests were unsuccessful, skipping publishing."
+        exit 1
+
+    #
+    # Install from sources
+    #
+    - name: Checkout ElastiCluster sources
+      # see: https://github.com/actions/checkout
+      uses: actions/checkout@v2
+      with:
+        persist-credentials: false
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: "3.7"
+
+    - name: Install `pip` and `setuptools`
+      run: "pip install --upgrade 'setuptools' 'pip>=8.1.2'"
+
+    - name: Install ElastiCluster from sources
+      run: "pip install -e ."
+
+    #
+    # Upload Docker image
+    #
+    - name: Publish to DockerHub
+      uses: elgohr/Publish-Docker-Github-Action@master
+      with:
+        name: "riccardomurri/elasticluster"
+        username: ${{ secrets.DOCKER_USER }}
+        password: ${{ secrets.DOCKER_PASS }}
+
+        # FIXME: we occasionally might want to also publish artifacts from PRs,
+        # in which case the `tags:` line should *not* include `latest` and be only
+        # `tags: pr-${{ github.event.number }}`  But it is dangerous to automatically
+        # do this, as contributors could modify these workflows as well, so PR publishing
+        # should always be a manual action.
+        tags: "latest,${{ github.head_ref }}"
+
+        # push tags/release by their git name (e.g. refs/tags/MY_TAG_NAME)
+        tag_names: true
+
+        # push tags using the semver syntax by their git name
+        # (e.g. refs/tags/v1.2.3 will push four docker tags: 1.2.3, 1.2 and 1)
+        tag_semver: true
+
+    - name: Success
+      run: |
+        echo "OK: Docker image successfully pushed."
+        exit 0

.github/workflows/tests.yml

@@ -0,0 +1,156 @@
+name: Tests
+
+on:
+  push:
+  pull_request:
+    types:
+      - opened
+      - ready_for_review
+      - review_request_removed
+      - synchronize
+      - reopened
+
+jobs:
+  unit-tests:
+    name: Run Unit Tests
+    strategy:
+      # we want to know which Python's pass and which fail
+      fail-fast: false
+      matrix:
+        # use the `matrix: include:` trick to build a simple list of
+        # parameters; we only need to override some package versions in
+        # specific cases (e.g., Python 2.7 needs older `setuptools` and `pip`)
+        include:
+
+          - python: "2.7"
+            # as of 2021-01-05, setuptools 51 and pip 21 have dropped support
+            # for Py 2.7 completely, so we need to use earlier versions to
+            # continue testing
+            prerequisites: "'setuptools<=44.1.1' 'pip==20.3.3'"
+
+          - python: "3.5"
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+
+          - python: "3.6"
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+
+          - python: "3.7"
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+
+          - python: "3.8"
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+
+          - python: "3.9"
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+
+    env:
+      PYTHON: ${{ matrix.python }}
+
+    runs-on: ubuntu-latest
+    steps:
+
+    - name: Show Python location and version
+      run: |
+        # display data about Python interpreter
+        set -e
+        echo "Python executable: $(command -v python)"
+        echo "Python version: $(python -V 2>&1)"
+
+    #
+    # Install from sources
+    #
+    - name: Checkout ElastiCluster sources
+      # see: https://github.com/actions/checkout
+      uses: actions/checkout@v2
+      with:
+        persist-credentials: false
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python }}
+
+    - name: Install `pip` and `setuptools`
+      run: "pip install --upgrade ${{ matrix.prerequisites }}"
+
+    - name: Install ElastiCluster from sources
+      run: "pip install -e ."
+
+    #
+    # Unit tests
+    #
+    - name: Install test dependencies
+      run: "pip install 'pytest>=2.10' 'pytest-cov' 'mock' 'tox' 'codecov'"
+
+    - name: Run unit tests
+      run: "pytest -v --cov=elasticluster --cov-branch"
+
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v1
+      with:
+        flags: unittests
+        env_vars: PYTHON
+
+    - name: Success
+      run: |
+        echo "OK: ElastiCluster's unit tests successfully performed."
+        exit 0
+
+
+  install-tests:
+    name: Test installation on different OSes
+    strategy:
+      matrix:
+        env:
+          - os: ubuntu-20.04
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+            path: "/home/runner/.local/bin"
+          - os: ubuntu-18.04
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+            path: "/home/runner/.local/bin"
+          - os: ubuntu-16.04
+            prerequisites: "'setuptools<=44.1.1' 'pip==20.3.3'"
+            path: "/home/runner/.local/bin"
+          - os: macos-11.0
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+            path: '/Library/Frameworks/Python.framework/Versions/2.7/bin'
+          - os: macos-10.15
+            prerequisites: "'setuptools>=21' 'pip>=9.0.0'"
+            path: '/Library/Frameworks/Python.framework/Versions/2.7/bin'
+      # we want to know which OSes pass and which fail
+      fail-fast: false
+
+    runs-on: ${{ matrix.env.os }}
+    steps:
+
+    - name: Show Python location and version
+      run: |
+        # display data about Python interpreter
+        echo "Python executable: $(command -v python)"
+        echo "Python version: $(python -V 2>&1)"
+
+    #
+    # Install from sources
+    #
+    - name: Checkout ElastiCluster sources
+      # see: https://github.com/actions/checkout
+      uses: actions/checkout@v2
+      with:
+        persist-credentials: false
+
+    - name: Install `pip` and `setuptools`
+      run: "pip install --upgrade ${{ matrix.env.prerequisites }}"
+
+    - name: Install ElastiCluster from sources
+      run: "pip install ."
+
+    - name: Try running `elasticluster` commands
+      run: |
+        # different incantations of the `elasticluster` command
+        export PATH="$PATH:${{ matrix.env.path }}"
+        elasticluster --version
+        elasticluster list-templates
+
+    - name: Success
+      run: |
+        echo "OK: ElastiCluster successfully installed."
+        exit 0

tests/test_cli.py

@@ -21,13 +21,10 @@
 from future import standard_library
 standard_library.install_aliases()
 
-from io import StringIO
 import os
 import subprocess
 import sys
 
-import pytest
-
 from elasticluster.utils import temporary_dir, environment
 
 __author__ = (', '.join([
@@ -37,14 +34,29 @@
 
 
 # TODO: Could be a parametric fixture I guess
-def _run_command(argv):
+def _run_elasticluster_cmd(argv):
     """
     Run the `elasticluster` command with additional arguments.
 
     Return STDOUT, STDERR, and the process exit status.
     """
     with temporary_dir() as tmpdir:
-        with environment(HOME=os.getcwd()) as env:
+        with environment(
+            HOME=os.getcwd(),
+            PYTHONWARNINGS=(
+                # as support for Py2 wanes, we must silence warnings that
+                # Python 2.7 will no longer be supported, as they make the
+                # tests fail unnecessarily (functionality is OK, we just get
+                # some extra lines into STDERR). However,
+                # `cryptography.utils.CryptographyDeprecationWarning` is a
+                # subclass of `UserWarning` exactly because
+                # `DeprecationWarnings` are ignored by default, so we need to
+                # ignore all `UserWarnings` as well (cannot ignore a non-builtin
+                # exception class via an environmental variable)
+                'ignore::DeprecationWarning,ignore::UserWarning' if sys.version_info < (3, 6)
+                # display all warnings on Py3.6+
+                else ''),
+        ) as env:
             proc = subprocess.Popen(
                 ['elasticluster'] + argv,
                 stdin=None,
@@ -57,22 +69,22 @@ def _run_command(argv):
 
 
 def test_cli_help():
-    out, err, code = _run_command(["--help"])
+    out, err, code = _run_elasticluster_cmd(["--help"])
     assert out.startswith(b"usage: elasticluster [-h] [-v]")
     assert not err
     assert not code
 
 
 def test_cli_version():
     from elasticluster import __version__ as elasticluster_version
-    out, err, code = _run_command(["--version"])
+    out, err, code = _run_elasticluster_cmd(["--version"])
     assert not err
     assert not code
     assert out.rstrip() == ("elasticluster version {0}".format(elasticluster_version)).encode('ascii')
 
 
 def test_cli_list_default(tmpdir):
-    out, err, code = _run_command(["list"])
+    out, err, code = _run_elasticluster_cmd(["list"])
     assert out.rstrip() == b"No clusters found."
     # default configuration is insufficient
     assert b"references non-existing login section" in err